Photo catalytic device for continuous process for co-conversion of co2+h2o to c1-oxygenates in sunlight

Abstract

The present invention discloses a dual functional photocatalytic device and a process for photocatalytic co-conversion of CO 2 and H 2 O to value added products in direct sunlight. More particularly, the present invention relates to efficient and continuous process for the photocatalytic co-conversion of a mixture of CO 2 and water into methanol, formaldehyde, in the presence of newly developed dual-functional photocatalyst device. The present invention is to provide dual-functional photocatalyst device, along with a co-catalyst and integrating them into a photocatalytic device using artificial leaf approach wherein said device is in the form of thin film working under wide spectrum of solar radiation at ambient conditions. Additionally it is easy to scale up the photocatalyst device size from 1 cm 2 to 10 cm 2 size and process is tuneable to generate desired products.

1 . A dual functional photocatalytic device comprising:
 i) a Visible-light absorbing semiconductor [VAS] assembled in the pores of wide band gap semiconductor called photoanode; and   ii) integrated with a co-catalyst in thin film form;   wherein   Visible-light absorbing semiconductor [VAS] is selected from the group comprising of earth abundant 3d or 4d transition metals, metal oxides alone or in combinations thereof;   wide gap semiconductor is selected from TiO 2  or ZnO;   Co-catalyst is selected from the group comprising of earth abundant 3d or 4d transition metals, metal oxides alone or in combination thereof.   
     
     
         2 . The device as claimed in  claim 1 , wherein said Visible-light absorbing semiconductor [VAS] used is selected from the group comprising of BiVO 4 , CdS and PbS. 
     
     
         3 . The device as claimed in  claim 1 , wherein said Visible-light absorbing semiconductor [VAS] is in the mesopores of the wide band gap semiconductor in the form of quantum dots (QDs). 
     
     
         4 . The device as claimed in  claim 1 , wherein said co-catalyst is selected from the group consisting of nano palladum (Pd), Platinum (Pt), Gold (Au), Silver (Ag), Nickel (Ni), Cobalt (Co), Cuprous oxide (Cu 2 O), NiCu alloy, Ti, Si or Zn, Nickel oxide, manganese oxide, Iron oxides, NiFe, 0.5θ Pt @NiFe, 0.5θPt @NiCu, 0.5θ Pt @Pd, NiFe alloy or Pt-coated NiCu alloy. 
     
     
         5 . The device as claimed in  claim 1 , wherein said device shows stable activity for 50 h while maintaining product yield and selectivity. 
     
     
         6 . (canceled) 
     
     
         7 . A process for the photocatalytic co-conversion of a mixture of CO 2  and water to value added products in batch mode comprising the step of:
 i) injecting CO 2  into a water to maximum saturation level and placing a photocatalytic device of  claim 1  in a quartz reactor under light source at a temperature in the range of 1 to 60° C.;   wherein said light source used selected from U+Visible light, visible light and direct sunlight.   
     
     
         8 . A process for the photocatalytic co-conversion of a mixture of CO 2  and water to value added products in continuous mode comprising the step of:
 i) continuously flowing CO 2  through water with photocatalytic device of  claim 1  in a quartz reactor under light source at a temperature in the range of 1-60° C.;   wherein said light source used is selected from UV+Visible light, visible light and direct sunlight.   
     
     
         9 . The process as claimed in  claim 7 , wherein value added product is selected from methanol and formaldehyde. 
     
     
         10 . The process as claimed in  claims 7 , wherein conversion efficiency of said carbon dioxide to value added products is in the range of 35-55%. 
     
     
         11 . The process as claimed in  claims 7 , wherein said process is tunable to generate desired value-added products selected from methanol and formaldehyde. 
     
     
         12 . The process as claimed in  claim 8 , wherein value added product is selected from methanol and formaldehyde. 
     
     
         13 . The process as claimed in  claim 8 , wherein conversion efficiency of said carbon dioxide to value added products is in the range of 35-55%. 
     
     
         14 . The process as claimed in  claim 8 , wherein said process is tunable to generate desired value-added products selected from methanol and formaldehyde.